/*!
# D3D12 backend internals.

## Resource transitions

Vulkan semantics for resource states doesn't exactly match D3D12.

For regular images, whenever there is a specific layout used,
we map it to a corresponding D3D12 resource state.

For the swapchain images, we consider them to be in COMMON state
everywhere except for render passes, where it's forcefully
transitioned into the render state. When transfers to/from are
requested, we transition them into and from the COPY_ states.

For buffers and images in General layout, we the best effort of guessing
the single mutable state based on the access flags. We can't reliably
handle a case where multiple mutable access flags are used.
*/

#[macro_use]
extern crate bitflags;
#[macro_use]
extern crate log;

mod command;
mod conv;
mod descriptors_cpu;
mod device;
mod internal;
mod pool;
mod resource;
mod root_constants;
mod window;

use auxil::FastHashMap;
use hal::{
    adapter, format as f, image, memory, pso::PipelineStage, queue as q, Features, Hints, Limits,
};
use range_alloc::RangeAllocator;

use parking_lot::{Mutex, RwLock};
use smallvec::SmallVec;
use winapi::{
    shared::{dxgi, dxgi1_2, dxgi1_4, dxgi1_6, minwindef::TRUE, winerror},
    um::{d3d12, d3d12sdklayers, handleapi, synchapi, winbase},
    Interface,
};

use std::{
    borrow::Borrow,
    ffi::OsString,
    fmt,
    mem,
    os::windows::ffi::OsStringExt,
    //TODO: use parking_lot
    sync::Arc,
};

use self::descriptors_cpu::DescriptorCpuPool;

#[derive(Debug)]
pub(crate) struct HeapProperties {
    pub page_property: d3d12::D3D12_CPU_PAGE_PROPERTY,
    pub memory_pool: d3d12::D3D12_MEMORY_POOL,
}

// https://msdn.microsoft.com/de-de/library/windows/desktop/dn770377(v=vs.85).aspx
// Only 16 input slots allowed.
const MAX_VERTEX_BUFFERS: usize = 16;
const MAX_DESCRIPTOR_SETS: usize = 8;

const NUM_HEAP_PROPERTIES: usize = 3;

pub type DescriptorIndex = u64;

// Memory types are grouped according to the supported resources.
// Grouping is done to circumvent the limitations of heap tier 1 devices.
// Devices with Tier 1 will expose `BuffersOnly`, `ImageOnly` and `TargetOnly`.
// Devices with Tier 2 or higher will only expose `Universal`.
enum MemoryGroup {
    Universal = 0,
    BufferOnly,
    ImageOnly,
    TargetOnly,

    NumGroups,
}

// https://msdn.microsoft.com/de-de/library/windows/desktop/dn788678(v=vs.85).aspx
static HEAPS_NUMA: [HeapProperties; NUM_HEAP_PROPERTIES] = [
    // DEFAULT
    HeapProperties {
        page_property: d3d12::D3D12_CPU_PAGE_PROPERTY_NOT_AVAILABLE,
        memory_pool: d3d12::D3D12_MEMORY_POOL_L1,
    },
    // UPLOAD
    HeapProperties {
        page_property: d3d12::D3D12_CPU_PAGE_PROPERTY_WRITE_COMBINE,
        memory_pool: d3d12::D3D12_MEMORY_POOL_L0,
    },
    // READBACK
    HeapProperties {
        page_property: d3d12::D3D12_CPU_PAGE_PROPERTY_WRITE_BACK,
        memory_pool: d3d12::D3D12_MEMORY_POOL_L0,
    },
];

static HEAPS_UMA: [HeapProperties; NUM_HEAP_PROPERTIES] = [
    // DEFAULT
    HeapProperties {
        page_property: d3d12::D3D12_CPU_PAGE_PROPERTY_NOT_AVAILABLE,
        memory_pool: d3d12::D3D12_MEMORY_POOL_L0,
    },
    // UPLOAD
    HeapProperties {
        page_property: d3d12::D3D12_CPU_PAGE_PROPERTY_WRITE_COMBINE,
        memory_pool: d3d12::D3D12_MEMORY_POOL_L0,
    },
    // READBACK
    HeapProperties {
        page_property: d3d12::D3D12_CPU_PAGE_PROPERTY_WRITE_BACK,
        memory_pool: d3d12::D3D12_MEMORY_POOL_L0,
    },
];

static HEAPS_CCUMA: [HeapProperties; NUM_HEAP_PROPERTIES] = [
    // DEFAULT
    HeapProperties {
        page_property: d3d12::D3D12_CPU_PAGE_PROPERTY_NOT_AVAILABLE,
        memory_pool: d3d12::D3D12_MEMORY_POOL_L0,
    },
    // UPLOAD
    HeapProperties {
        page_property: d3d12::D3D12_CPU_PAGE_PROPERTY_WRITE_BACK,
        memory_pool: d3d12::D3D12_MEMORY_POOL_L0,
    },
    //READBACK
    HeapProperties {
        page_property: d3d12::D3D12_CPU_PAGE_PROPERTY_WRITE_BACK,
        memory_pool: d3d12::D3D12_MEMORY_POOL_L0,
    },
];

#[derive(Debug, Copy, Clone)]
pub enum QueueFamily {
    // Specially marked present queue.
    // It's basically a normal 3D queue but D3D12 swapchain creation requires an
    // associated queue, which we don't know on `create_swapchain`.
    Present,
    Normal(q::QueueType),
}

const MAX_QUEUES: usize = 16; // infinite, to be fair

impl q::QueueFamily for QueueFamily {
    fn queue_type(&self) -> q::QueueType {
        match *self {
            QueueFamily::Present => q::QueueType::General,
            QueueFamily::Normal(ty) => ty,
        }
    }
    fn max_queues(&self) -> usize {
        match *self {
            QueueFamily::Present => 1,
            QueueFamily::Normal(_) => MAX_QUEUES,
        }
    }
    fn id(&self) -> q::QueueFamilyId {
        // This must match the order exposed by `QUEUE_FAMILIES`
        q::QueueFamilyId(match *self {
            QueueFamily::Present => 0,
            QueueFamily::Normal(q::QueueType::General) => 1,
            QueueFamily::Normal(q::QueueType::Compute) => 2,
            QueueFamily::Normal(q::QueueType::Transfer) => 3,
            _ => unreachable!(),
        })
    }
}

impl QueueFamily {
    fn native_type(&self) -> native::CmdListType {
        use hal::queue::QueueFamily as _;
        use native::CmdListType as Clt;

        let queue_type = self.queue_type();
        match queue_type {
            q::QueueType::General | q::QueueType::Graphics => Clt::Direct,
            q::QueueType::Compute => Clt::Compute,
            q::QueueType::Transfer => Clt::Copy,
        }
    }
}

static QUEUE_FAMILIES: [QueueFamily; 4] = [
    QueueFamily::Present,
    QueueFamily::Normal(q::QueueType::General),
    QueueFamily::Normal(q::QueueType::Compute),
    QueueFamily::Normal(q::QueueType::Transfer),
];

#[derive(Default)]
struct Workarounds {
    // On WARP, temporary CPU descriptors are still used by the runtime
    // after we call `CopyDescriptors`.
    avoid_cpu_descriptor_overwrites: bool,
}

//Note: fields are dropped in the order of declaration, so we put the
// most owning fields last.
pub struct PhysicalDevice {
    features: Features,
    hints: Hints,
    limits: Limits,
    format_properties: Arc<FormatProperties>,
    private_caps: Capabilities,
    workarounds: Workarounds,
    heap_properties: &'static [HeapProperties; NUM_HEAP_PROPERTIES],
    memory_properties: adapter::MemoryProperties,
    // Indicates that there is currently an active logical device.
    // Opening the same adapter multiple times will return the same D3D12Device again.
    is_open: Arc<Mutex<bool>>,
    adapter: native::WeakPtr<dxgi1_2::IDXGIAdapter2>,
    library: Arc<native::D3D12Lib>,
}

impl fmt::Debug for PhysicalDevice {
    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
        fmt.write_str("PhysicalDevice")
    }
}

unsafe impl Send for PhysicalDevice {}
unsafe impl Sync for PhysicalDevice {}

impl adapter::PhysicalDevice<Backend> for PhysicalDevice {
    unsafe fn open(
        &self,
        families: &[(&QueueFamily, &[q::QueuePriority])],
        requested_features: Features,
    ) -> Result<adapter::Gpu<Backend>, hal::device::CreationError> {
        let mut open_guard = match self.is_open.try_lock() {
            Some(inner) => inner,
            None => return Err(hal::device::CreationError::TooManyObjects),
        };

        if !self.features().contains(requested_features) {
            return Err(hal::device::CreationError::MissingFeature);
        }

        let device_raw = match self
            .library
            .create_device(self.adapter, native::FeatureLevel::L11_0)
        {
            Ok((device, hr)) if winerror::SUCCEEDED(hr) => device,
            Ok((_, hr)) => {
                error!("error on device creation: {:x}", hr);
                return Err(hal::device::CreationError::InitializationFailed);
            }
            Err(e) => panic!("device creation failed with {:?}", e),
        };

        // Always create the presentation queue in case we want to build a swapchain.
        let (present_queue, hr_queue) = device_raw.create_command_queue(
            QueueFamily::Present.native_type(),
            native::Priority::Normal,
            native::CommandQueueFlags::empty(),
            0,
        );
        if !winerror::SUCCEEDED(hr_queue) {
            error!("error on queue creation: {:x}", hr_queue);
        }

        let mut device = Device::new(device_raw, &self, present_queue);
        device.features = requested_features;

        let queue_groups = families
            .into_iter()
            .map(|&(&family, priorities)| {
                use hal::queue::QueueFamily as _;
                let mut group = q::QueueGroup::new(family.id());

                let create_idle_event = || native::Event::create(true, false);

                match family {
                    QueueFamily::Present => {
                        // Exactly **one** present queue!
                        // Number of queues need to be larger than 0 else it
                        // violates the specification.
                        let queue = CommandQueue {
                            raw: device.present_queue.clone(),
                            idle_fence: device.create_raw_fence(false),
                            idle_event: create_idle_event(),
                        };
                        device.append_queue(queue.clone());
                        group.add_queue(queue);
                    }
                    QueueFamily::Normal(_) => {
                        let list_type = family.native_type();
                        for _ in 0..priorities.len() {
                            let (queue, hr_queue) = device_raw.create_command_queue(
                                list_type,
                                native::Priority::Normal,
                                native::CommandQueueFlags::empty(),
                                0,
                            );

                            if winerror::SUCCEEDED(hr_queue) {
                                let queue = CommandQueue {
                                    raw: queue,
                                    idle_fence: device.create_raw_fence(false),
                                    idle_event: create_idle_event(),
                                };
                                device.append_queue(queue.clone());
                                group.add_queue(queue);
                            } else {
                                error!("error on queue creation: {:x}", hr_queue);
                            }
                        }
                    }
                }

                group
            })
            .collect();

        *open_guard = true;

        Ok(adapter::Gpu {
            device,
            queue_groups,
        })
    }

    fn format_properties(&self, fmt: Option<f::Format>) -> f::Properties {
        let idx = fmt.map(|fmt| fmt as usize).unwrap_or(0);
        self.format_properties.resolve(idx).properties
    }

    fn image_format_properties(
        &self,
        format: f::Format,
        dimensions: u8,
        tiling: image::Tiling,
        usage: image::Usage,
        view_caps: image::ViewCapabilities,
    ) -> Option<image::FormatProperties> {
        conv::map_format(format)?; //filter out unknown formats
        let format_info = self.format_properties.resolve(format as usize);

        let supported_usage = {
            use hal::image::Usage as U;
            let props = match tiling {
                image::Tiling::Optimal => format_info.properties.optimal_tiling,
                image::Tiling::Linear => format_info.properties.linear_tiling,
            };
            let mut flags = U::empty();
            // Note: these checks would have been nicer if we had explicit BLIT usage
            if props.contains(f::ImageFeature::BLIT_SRC) {
                flags |= U::TRANSFER_SRC;
            }
            if props.contains(f::ImageFeature::BLIT_DST) {
                flags |= U::TRANSFER_DST;
            }
            if props.contains(f::ImageFeature::SAMPLED) {
                flags |= U::SAMPLED;
            }
            if props.contains(f::ImageFeature::STORAGE) {
                flags |= U::STORAGE;
            }
            if props.contains(f::ImageFeature::COLOR_ATTACHMENT) {
                flags |= U::COLOR_ATTACHMENT;
            }
            if props.contains(f::ImageFeature::DEPTH_STENCIL_ATTACHMENT) {
                flags |= U::DEPTH_STENCIL_ATTACHMENT;
            }
            flags
        };
        if !supported_usage.contains(usage) {
            return None;
        }

        let max_resource_size =
            (d3d12::D3D12_REQ_RESOURCE_SIZE_IN_MEGABYTES_EXPRESSION_A_TERM as usize) << 20;
        Some(match tiling {
            image::Tiling::Optimal => image::FormatProperties {
                max_extent: match dimensions {
                    1 => image::Extent {
                        width: d3d12::D3D12_REQ_TEXTURE1D_U_DIMENSION,
                        height: 1,
                        depth: 1,
                    },
                    2 => image::Extent {
                        width: d3d12::D3D12_REQ_TEXTURE2D_U_OR_V_DIMENSION,
                        height: d3d12::D3D12_REQ_TEXTURE2D_U_OR_V_DIMENSION,
                        depth: 1,
                    },
                    3 => image::Extent {
                        width: d3d12::D3D12_REQ_TEXTURE3D_U_V_OR_W_DIMENSION,
                        height: d3d12::D3D12_REQ_TEXTURE3D_U_V_OR_W_DIMENSION,
                        depth: d3d12::D3D12_REQ_TEXTURE3D_U_V_OR_W_DIMENSION,
                    },
                    _ => return None,
                },
                max_levels: d3d12::D3D12_REQ_MIP_LEVELS as _,
                max_layers: match dimensions {
                    1 => d3d12::D3D12_REQ_TEXTURE1D_ARRAY_AXIS_DIMENSION as _,
                    2 => d3d12::D3D12_REQ_TEXTURE2D_ARRAY_AXIS_DIMENSION as _,
                    _ => return None,
                },
                sample_count_mask: if dimensions == 2
                    && !view_caps.contains(image::ViewCapabilities::KIND_CUBE)
                    && !usage.contains(image::Usage::STORAGE)
                {
                    format_info.sample_count_mask
                } else {
                    0x1
                },
                max_resource_size,
            },
            image::Tiling::Linear => image::FormatProperties {
                max_extent: match dimensions {
                    2 => image::Extent {
                        width: d3d12::D3D12_REQ_TEXTURE2D_U_OR_V_DIMENSION,
                        height: d3d12::D3D12_REQ_TEXTURE2D_U_OR_V_DIMENSION,
                        depth: 1,
                    },
                    _ => return None,
                },
                max_levels: 1,
                max_layers: 1,
                sample_count_mask: 0x1,
                max_resource_size,
            },
        })
    }

    fn memory_properties(&self) -> adapter::MemoryProperties {
        self.memory_properties.clone()
    }

    fn features(&self) -> Features {
        self.features
    }

    fn hints(&self) -> Hints {
        self.hints
    }

    fn limits(&self) -> Limits {
        self.limits
    }
}

#[derive(Clone)]
pub struct CommandQueue {
    pub(crate) raw: native::CommandQueue,
    idle_fence: native::Fence,
    idle_event: native::Event,
}

impl fmt::Debug for CommandQueue {
    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
        fmt.write_str("CommandQueue")
    }
}

impl CommandQueue {
    unsafe fn destroy(&self) {
        handleapi::CloseHandle(self.idle_event.0);
        self.idle_fence.destroy();
        self.raw.destroy();
    }
}

unsafe impl Send for CommandQueue {}
unsafe impl Sync for CommandQueue {}

impl q::CommandQueue<Backend> for CommandQueue {
    unsafe fn submit<'a, T, Ic, S, Iw, Is>(
        &mut self,
        submission: q::Submission<Ic, Iw, Is>,
        fence: Option<&resource::Fence>,
    ) where
        T: 'a + Borrow<command::CommandBuffer>,
        Ic: IntoIterator<Item = &'a T>,
        S: 'a + Borrow<resource::Semaphore>,
        Iw: IntoIterator<Item = (&'a S, PipelineStage)>,
        Is: IntoIterator<Item = &'a S>,
    {
        // Reset idle fence and event
        // That's safe here due to exclusive access to the queue
        self.idle_fence.signal(0);
        synchapi::ResetEvent(self.idle_event.0);

        // TODO: semaphores
        let lists = submission
            .command_buffers
            .into_iter()
            .map(|cmd_buf| cmd_buf.borrow().as_raw_list())
            .collect::<SmallVec<[_; 4]>>();
        self.raw
            .ExecuteCommandLists(lists.len() as _, lists.as_ptr());

        if let Some(fence) = fence {
            assert_eq!(winerror::S_OK, self.raw.Signal(fence.raw.as_mut_ptr(), 1));
        }
    }

    unsafe fn present(
        &mut self,
        surface: &mut window::Surface,
        image: window::SwapchainImage,
        _wait_semaphore: Option<&resource::Semaphore>,
    ) -> Result<Option<hal::window::Suboptimal>, hal::window::PresentError> {
        surface.present(image).map(|()| None)
    }

    fn wait_idle(&self) -> Result<(), hal::device::OutOfMemory> {
        self.raw.signal(self.idle_fence, 1);
        assert_eq!(
            winerror::S_OK,
            self.idle_fence.set_event_on_completion(self.idle_event, 1)
        );

        unsafe {
            synchapi::WaitForSingleObject(self.idle_event.0, winbase::INFINITE);
        }

        Ok(())
    }
}

#[derive(Debug, Clone, Copy)]
enum MemoryArchitecture {
    NUMA,
    UMA,
    CacheCoherentUMA,
}

#[derive(Debug, Clone, Copy)]
pub struct Capabilities {
    heterogeneous_resource_heaps: bool,
    memory_architecture: MemoryArchitecture,
}

#[derive(Clone, Debug)]
struct CmdSignatures {
    draw: native::CommandSignature,
    draw_indexed: native::CommandSignature,
    dispatch: native::CommandSignature,
}

impl CmdSignatures {
    unsafe fn destroy(&self) {
        self.draw.destroy();
        self.draw_indexed.destroy();
        self.dispatch.destroy();
    }
}

// Shared objects between command buffers, owned by the device.
#[derive(Debug)]
struct Shared {
    pub signatures: CmdSignatures,
    pub service_pipes: internal::ServicePipes,
}

impl Shared {
    unsafe fn destroy(&self) {
        self.signatures.destroy();
        self.service_pipes.destroy();
    }
}

pub struct SamplerStorage {
    map: Mutex<FastHashMap<image::SamplerDesc, descriptors_cpu::Handle>>,
    pool: Mutex<DescriptorCpuPool>,
    heap: resource::DescriptorHeap,
    origins: RwLock<resource::DescriptorOrigins>,
}

impl SamplerStorage {
    unsafe fn destroy(&mut self) {
        self.pool.lock().destroy();
        self.heap.destroy();
    }
}

pub struct Device {
    raw: native::Device,
    private_caps: Capabilities,
    features: Features,
    format_properties: Arc<FormatProperties>,
    heap_properties: &'static [HeapProperties],
    // CPU only pools
    rtv_pool: Mutex<DescriptorCpuPool>,
    dsv_pool: Mutex<DescriptorCpuPool>,
    srv_uav_pool: Mutex<DescriptorCpuPool>,
    descriptor_updater: Mutex<descriptors_cpu::DescriptorUpdater>,
    // CPU/GPU descriptor heaps
    heap_srv_cbv_uav: (
        resource::DescriptorHeap,
        Mutex<RangeAllocator<DescriptorIndex>>,
    ),
    samplers: SamplerStorage,
    events: Mutex<Vec<native::Event>>,
    shared: Arc<Shared>,
    // Present queue exposed by the `Present` queue family.
    // Required for swapchain creation. Only a single queue supports presentation.
    present_queue: native::CommandQueue,
    // List of all queues created from this device, including present queue.
    // Needed for `wait_idle`.
    queues: Vec<CommandQueue>,
    // Indicates that there is currently an active device.
    open: Arc<Mutex<bool>>,
    library: Arc<native::D3D12Lib>,
}

impl fmt::Debug for Device {
    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
        fmt.write_str("Device")
    }
}

unsafe impl Send for Device {} //blocked by ComPtr
unsafe impl Sync for Device {} //blocked by ComPtr

impl Device {
    fn new(
        device: native::Device,
        physical_device: &PhysicalDevice,
        present_queue: native::CommandQueue,
    ) -> Self {
        // Allocate descriptor heaps
        let rtv_pool = DescriptorCpuPool::new(device, native::DescriptorHeapType::Rtv);
        let dsv_pool = DescriptorCpuPool::new(device, native::DescriptorHeapType::Dsv);
        let srv_uav_pool = DescriptorCpuPool::new(device, native::DescriptorHeapType::CbvSrvUav);

        // maximum number of CBV/SRV/UAV descriptors in heap for Tier 1
        let view_capacity = 1_000_000;
        let heap_srv_cbv_uav = Self::create_descriptor_heap_impl(
            device,
            native::DescriptorHeapType::CbvSrvUav,
            true,
            view_capacity,
        );
        let view_range_allocator = RangeAllocator::new(0..(view_capacity as u64));

        let sampler_pool = DescriptorCpuPool::new(device, native::DescriptorHeapType::Sampler);
        let heap_sampler = Self::create_descriptor_heap_impl(
            device,
            native::DescriptorHeapType::Sampler,
            true,
            2_048,
        );

        let descriptor_updater = descriptors_cpu::DescriptorUpdater::new(
            device,
            physical_device.workarounds.avoid_cpu_descriptor_overwrites,
        );

        let draw_signature = Self::create_command_signature(device, device::CommandSignature::Draw);
        let draw_indexed_signature =
            Self::create_command_signature(device, device::CommandSignature::DrawIndexed);
        let dispatch_signature =
            Self::create_command_signature(device, device::CommandSignature::Dispatch);

        let signatures = CmdSignatures {
            draw: draw_signature,
            draw_indexed: draw_indexed_signature,
            dispatch: dispatch_signature,
        };
        let service_pipes =
            internal::ServicePipes::new(device, Arc::clone(&physical_device.library));
        let shared = Shared {
            signatures,
            service_pipes,
        };

        Device {
            raw: device,
            library: Arc::clone(&physical_device.library),
            private_caps: physical_device.private_caps,
            features: Features::empty(),
            format_properties: physical_device.format_properties.clone(),
            heap_properties: physical_device.heap_properties,
            rtv_pool: Mutex::new(rtv_pool),
            dsv_pool: Mutex::new(dsv_pool),
            srv_uav_pool: Mutex::new(srv_uav_pool),
            descriptor_updater: Mutex::new(descriptor_updater),
            heap_srv_cbv_uav: (heap_srv_cbv_uav, Mutex::new(view_range_allocator)),
            samplers: SamplerStorage {
                map: Mutex::default(),
                pool: Mutex::new(sampler_pool),
                heap: heap_sampler,
                origins: RwLock::default(),
            },
            events: Mutex::new(Vec::new()),
            shared: Arc::new(shared),
            present_queue,
            queues: Vec::new(),
            open: Arc::clone(&physical_device.is_open),
        }
    }

    fn append_queue(&mut self, queue: CommandQueue) {
        self.queues.push(queue);
    }

    /// Get the native d3d12 device.
    ///
    /// Required for FFI with libraries like RenderDoc.
    pub unsafe fn as_raw(&self) -> *mut d3d12::ID3D12Device {
        self.raw.as_mut_ptr()
    }
}

impl Drop for Device {
    fn drop(&mut self) {
        *self.open.lock() = false;

        unsafe {
            for queue in &mut self.queues {
                let _ = q::CommandQueue::wait_idle(queue);
                queue.destroy();
            }

            self.shared.destroy();
            self.heap_srv_cbv_uav.0.destroy();
            self.samplers.destroy();
            self.rtv_pool.lock().destroy();
            self.dsv_pool.lock().destroy();
            self.srv_uav_pool.lock().destroy();

            self.descriptor_updater.lock().destroy();

            // Debug tracking alive objects
            let (debug_device, hr_debug) = self.raw.cast::<d3d12sdklayers::ID3D12DebugDevice>();
            if winerror::SUCCEEDED(hr_debug) {
                debug_device.ReportLiveDeviceObjects(d3d12sdklayers::D3D12_RLDO_DETAIL);
                debug_device.destroy();
            }

            self.raw.destroy();
        }
    }
}

#[derive(Debug)]
pub struct Instance {
    pub(crate) factory: native::Factory4,
    library: Arc<native::D3D12Lib>,
    lib_dxgi: native::DxgiLib,
}

impl Drop for Instance {
    fn drop(&mut self) {
        unsafe {
            self.factory.destroy();
        }
    }
}

unsafe impl Send for Instance {}
unsafe impl Sync for Instance {}

impl hal::Instance<Backend> for Instance {
    fn create(_: &str, _: u32) -> Result<Self, hal::UnsupportedBackend> {
        let lib_main = match native::D3D12Lib::new() {
            Ok(lib) => lib,
            Err(_) => return Err(hal::UnsupportedBackend),
        };

        #[cfg(debug_assertions)]
        {
            // Enable debug layer
            match lib_main.get_debug_interface() {
                Ok((debug_controller, hr)) if winerror::SUCCEEDED(hr) => {
                    debug_controller.enable_layer();
                    unsafe {
                        debug_controller.Release();
                    }
                }
                _ => {
                    warn!("Unable to get D3D12 debug interface");
                }
            }
        }

        let lib_dxgi = native::DxgiLib::new().unwrap();

        // The `DXGI_CREATE_FACTORY_DEBUG` flag is only allowed to be passed to
        // `CreateDXGIFactory2` if the debug interface is actually available. So
        // we check for whether it exists first.
        let factory_flags = match lib_dxgi.get_debug_interface1() {
            Ok((queue, hr)) if winerror::SUCCEEDED(hr) => {
                unsafe { queue.destroy() };
                native::FactoryCreationFlags::DEBUG
            }
            _ => native::FactoryCreationFlags::empty(),
        };

        // Create DXGI factory
        let factory = match lib_dxgi.create_factory2(factory_flags) {
            Ok((factory, hr)) if winerror::SUCCEEDED(hr) => factory,
            Ok((_, hr)) => {
                info!("Failed on dxgi factory creation: {:?}", hr);
                return Err(hal::UnsupportedBackend);
            }
            Err(_) => return Err(hal::UnsupportedBackend),
        };

        Ok(Instance {
            factory,
            library: Arc::new(lib_main),
            lib_dxgi,
        })
    }

    fn enumerate_adapters(&self) -> Vec<adapter::Adapter<Backend>> {
        use self::memory::Properties;

        // Try to use high performance order by default (returns None on Windows < 1803)
        let (use_f6, factory6) = unsafe {
            let (f6, hr) = self.factory.cast::<dxgi1_6::IDXGIFactory6>();
            if winerror::SUCCEEDED(hr) {
                // It's okay to decrement the refcount here because we
                // have another reference to the factory already owned by `self`.
                f6.destroy();
                (true, f6)
            } else {
                (false, native::WeakPtr::null())
            }
        };

        // Enumerate adapters
        let mut cur_index = 0;
        let mut adapters = Vec::new();
        loop {
            let adapter = if use_f6 {
                let mut adapter2 = native::WeakPtr::<dxgi1_2::IDXGIAdapter2>::null();
                let hr = unsafe {
                    factory6.EnumAdapterByGpuPreference(
                        cur_index,
                        2, // HIGH_PERFORMANCE
                        &dxgi1_2::IDXGIAdapter2::uuidof(),
                        adapter2.mut_void() as *mut *mut _,
                    )
                };

                if hr == winerror::DXGI_ERROR_NOT_FOUND {
                    break;
                }
                if !winerror::SUCCEEDED(hr) {
                    error!("Failed enumerating adapters: 0x{:x}", hr);
                    break;
                }

                adapter2
            } else {
                let mut adapter1 = native::WeakPtr::<dxgi::IDXGIAdapter1>::null();
                let hr1 = unsafe {
                    self.factory
                        .EnumAdapters1(cur_index, adapter1.mut_void() as *mut *mut _)
                };

                if hr1 == winerror::DXGI_ERROR_NOT_FOUND {
                    break;
                }

                let (adapter2, hr2) = unsafe { adapter1.cast::<dxgi1_2::IDXGIAdapter2>() };
                if !winerror::SUCCEEDED(hr2) {
                    error!("Failed casting to Adapter2: 0x{:x}", hr2);
                    break;
                }

                unsafe {
                    adapter1.destroy();
                }
                adapter2
            };

            cur_index += 1;

            // Check for D3D12 support
            // Create temporary device to get physical device information
            let device = match self
                .library
                .create_device(adapter, native::FeatureLevel::L11_0)
            {
                Ok((device, hr)) if winerror::SUCCEEDED(hr) => device,
                _ => continue,
            };

            // We have found a possible adapter
            // acquire the device information
            let mut desc: dxgi1_2::DXGI_ADAPTER_DESC2 = unsafe { mem::zeroed() };
            unsafe {
                adapter.GetDesc2(&mut desc);
            }

            let device_name = {
                let len = desc.Description.iter().take_while(|&&c| c != 0).count();
                let name = <OsString as OsStringExt>::from_wide(&desc.Description[..len]);
                name.to_string_lossy().into_owned()
            };

            let mut features_architecture: d3d12::D3D12_FEATURE_DATA_ARCHITECTURE =
                unsafe { mem::zeroed() };
            assert_eq!(winerror::S_OK, unsafe {
                device.CheckFeatureSupport(
                    d3d12::D3D12_FEATURE_ARCHITECTURE,
                    &mut features_architecture as *mut _ as *mut _,
                    mem::size_of::<d3d12::D3D12_FEATURE_DATA_ARCHITECTURE>() as _,
                )
            });

            let mut workarounds = Workarounds::default();

            let info = adapter::AdapterInfo {
                name: device_name,
                vendor: desc.VendorId as usize,
                device: desc.DeviceId as usize,
                device_type: if (desc.Flags & dxgi::DXGI_ADAPTER_FLAG_SOFTWARE) != 0 {
                    workarounds.avoid_cpu_descriptor_overwrites = true;
                    adapter::DeviceType::VirtualGpu
                } else if features_architecture.CacheCoherentUMA == TRUE {
                    adapter::DeviceType::IntegratedGpu
                } else {
                    adapter::DeviceType::DiscreteGpu
                },
            };

            let mut features: d3d12::D3D12_FEATURE_DATA_D3D12_OPTIONS = unsafe { mem::zeroed() };
            assert_eq!(winerror::S_OK, unsafe {
                device.CheckFeatureSupport(
                    d3d12::D3D12_FEATURE_D3D12_OPTIONS,
                    &mut features as *mut _ as *mut _,
                    mem::size_of::<d3d12::D3D12_FEATURE_DATA_D3D12_OPTIONS>() as _,
                )
            });

            let depth_bounds_test_supported = {
                let mut features2: d3d12::D3D12_FEATURE_DATA_D3D12_OPTIONS2 =
                    unsafe { mem::zeroed() };
                let hr = unsafe {
                    device.CheckFeatureSupport(
                        d3d12::D3D12_FEATURE_D3D12_OPTIONS2,
                        &mut features2 as *mut _ as *mut _,
                        mem::size_of::<d3d12::D3D12_FEATURE_DATA_D3D12_OPTIONS2>() as _,
                    )
                };
                if hr == winerror::S_OK {
                    features2.DepthBoundsTestSupported != 0
                } else {
                    false
                }
            };

            let heterogeneous_resource_heaps =
                features.ResourceHeapTier != d3d12::D3D12_RESOURCE_HEAP_TIER_1;

            let uma = features_architecture.UMA == TRUE;
            let cc_uma = features_architecture.CacheCoherentUMA == TRUE;

            let (memory_architecture, heap_properties) = match (uma, cc_uma) {
                (true, true) => (MemoryArchitecture::CacheCoherentUMA, &HEAPS_CCUMA),
                (true, false) => (MemoryArchitecture::UMA, &HEAPS_UMA),
                (false, _) => (MemoryArchitecture::NUMA, &HEAPS_NUMA),
            };

            // https://msdn.microsoft.com/en-us/library/windows/desktop/dn788678(v=vs.85).aspx
            let base_memory_types: [adapter::MemoryType; NUM_HEAP_PROPERTIES] =
                match memory_architecture {
                    MemoryArchitecture::NUMA => [
                        // DEFAULT
                        adapter::MemoryType {
                            properties: Properties::DEVICE_LOCAL,
                            heap_index: 0,
                        },
                        // UPLOAD
                        adapter::MemoryType {
                            properties: Properties::CPU_VISIBLE | Properties::COHERENT,
                            heap_index: 1,
                        },
                        // READBACK
                        adapter::MemoryType {
                            properties: Properties::CPU_VISIBLE
                                | Properties::COHERENT
                                | Properties::CPU_CACHED,
                            heap_index: 1,
                        },
                    ],
                    MemoryArchitecture::UMA => [
                        // DEFAULT
                        adapter::MemoryType {
                            properties: Properties::DEVICE_LOCAL,
                            heap_index: 0,
                        },
                        // UPLOAD
                        adapter::MemoryType {
                            properties: Properties::DEVICE_LOCAL
                                | Properties::CPU_VISIBLE
                                | Properties::COHERENT,
                            heap_index: 0,
                        },
                        // READBACK
                        adapter::MemoryType {
                            properties: Properties::DEVICE_LOCAL
                                | Properties::CPU_VISIBLE
                                | Properties::COHERENT
                                | Properties::CPU_CACHED,
                            heap_index: 0,
                        },
                    ],
                    MemoryArchitecture::CacheCoherentUMA => [
                        // DEFAULT
                        adapter::MemoryType {
                            properties: Properties::DEVICE_LOCAL,
                            heap_index: 0,
                        },
                        // UPLOAD
                        adapter::MemoryType {
                            properties: Properties::DEVICE_LOCAL
                                | Properties::CPU_VISIBLE
                                | Properties::COHERENT
                                | Properties::CPU_CACHED,
                            heap_index: 0,
                        },
                        // READBACK
                        adapter::MemoryType {
                            properties: Properties::DEVICE_LOCAL
                                | Properties::CPU_VISIBLE
                                | Properties::COHERENT
                                | Properties::CPU_CACHED,
                            heap_index: 0,
                        },
                    ],
                };

            let memory_types = if heterogeneous_resource_heaps {
                base_memory_types.to_vec()
            } else {
                // We multiplicate the base memory types depending on the resource usage:
                //     0.. 3: Reserved for futures use
                //     4.. 6: Buffers
                //     7.. 9: Images
                //    10..12: Targets
                //
                // The supported memory types for a resource can be requested by asking for
                // the memory requirements. Memory type indices are encoded as bitflags.
                // `device::MEM_TYPE_MASK` (0b111) defines the bitmask for one base memory type group.
                // The corresponding shift masks (`device::MEM_TYPE_BUFFER_SHIFT`,
                // `device::MEM_TYPE_IMAGE_SHIFT`, `device::MEM_TYPE_TARGET_SHIFT`)
                // denote the usage group.
                let mut types = Vec::new();
                for i in 0..MemoryGroup::NumGroups as _ {
                    types.extend(base_memory_types.iter().map(|mem_type| {
                        let mut ty = mem_type.clone();

                        // Images and Targets are not host visible as we can't create
                        // a corresponding buffer for mapping.
                        if i == MemoryGroup::ImageOnly as _ || i == MemoryGroup::TargetOnly as _ {
                            ty.properties.remove(Properties::CPU_VISIBLE);
                            // Coherent and cached can only be on memory types that are cpu visible
                            ty.properties.remove(Properties::COHERENT);
                            ty.properties.remove(Properties::CPU_CACHED);
                        }
                        ty
                    }));
                }
                types
            };

            let memory_heaps = {
                // Get the IDXGIAdapter3 from the created device to query video memory information.
                let adapter_id = unsafe { device.GetAdapterLuid() };
                let adapter = {
                    let mut adapter = native::WeakPtr::<dxgi1_4::IDXGIAdapter3>::null();
                    unsafe {
                        assert_eq!(
                            winerror::S_OK,
                            self.factory.EnumAdapterByLuid(
                                adapter_id,
                                &dxgi1_4::IDXGIAdapter3::uuidof(),
                                adapter.mut_void(),
                            )
                        );
                    }
                    adapter
                };

                let query_memory = |segment: dxgi1_4::DXGI_MEMORY_SEGMENT_GROUP| unsafe {
                    let mut mem_info: dxgi1_4::DXGI_QUERY_VIDEO_MEMORY_INFO = mem::zeroed();
                    assert_eq!(
                        winerror::S_OK,
                        adapter.QueryVideoMemoryInfo(0, segment, &mut mem_info)
                    );
                    mem_info.Budget
                };

                let mut heaps = vec![adapter::MemoryHeap {
                    size: query_memory(dxgi1_4::DXGI_MEMORY_SEGMENT_GROUP_LOCAL),
                    flags: memory::HeapFlags::DEVICE_LOCAL,
                }];
                if let MemoryArchitecture::NUMA = memory_architecture {
                    heaps.push(adapter::MemoryHeap {
                        size: query_memory(dxgi1_4::DXGI_MEMORY_SEGMENT_GROUP_NON_LOCAL),
                        flags: memory::HeapFlags::empty(),
                    });
                }
                heaps
            };
            //TODO: find a way to get a tighter bound?
            let sample_count_mask = 0x3F;

            // Theoretically vram limited, but in practice 2^20 is the limit
            let tier3_practical_descriptor_limit = 1 << 20;

            let full_heap_count = match features.ResourceBindingTier {
                d3d12::D3D12_RESOURCE_BINDING_TIER_1 => {
                    d3d12::D3D12_MAX_SHADER_VISIBLE_DESCRIPTOR_HEAP_SIZE_TIER_1
                }
                d3d12::D3D12_RESOURCE_BINDING_TIER_2 => {
                    d3d12::D3D12_MAX_SHADER_VISIBLE_DESCRIPTOR_HEAP_SIZE_TIER_2
                }
                d3d12::D3D12_RESOURCE_BINDING_TIER_3 => tier3_practical_descriptor_limit,
                _ => unreachable!(),
            } as _;

            let uav_limit = match features.ResourceBindingTier {
                d3d12::D3D12_RESOURCE_BINDING_TIER_1 => 8, // conservative, is 64 on feature level 11.1
                d3d12::D3D12_RESOURCE_BINDING_TIER_2 => 64,
                d3d12::D3D12_RESOURCE_BINDING_TIER_3 => tier3_practical_descriptor_limit,
                _ => unreachable!(),
            } as _;

            let physical_device = PhysicalDevice {
                library: Arc::clone(&self.library),
                adapter,
                features:
                    // TODO: add more features, based on
                    // https://msdn.microsoft.com/de-de/library/windows/desktop/mt186615(v=vs.85).aspx
                    Features::ROBUST_BUFFER_ACCESS |
                    Features::IMAGE_CUBE_ARRAY |
                    Features::GEOMETRY_SHADER |
                    Features::TESSELLATION_SHADER |
                    Features::NON_FILL_POLYGON_MODE |
                    if depth_bounds_test_supported { Features::DEPTH_BOUNDS } else { Features::empty() } |
                    //logic_op: false, // Optional on feature level 11_0
                    Features::MULTI_DRAW_INDIRECT |
                    Features::FORMAT_BC |
                    Features::INSTANCE_RATE |
                    Features::DEPTH_CLAMP |
                    Features::SAMPLER_MIP_LOD_BIAS |
                    Features::SAMPLER_BORDER_COLOR |
                    Features::MUTABLE_COMPARISON_SAMPLER |
                    Features::SAMPLER_ANISOTROPY |
                    Features::TEXTURE_DESCRIPTOR_ARRAY |
                    Features::SAMPLER_MIRROR_CLAMP_EDGE |
                    Features::NDC_Y_UP |
                    Features::SHADER_SAMPLED_IMAGE_ARRAY_DYNAMIC_INDEXING |
                    Features::SHADER_STORAGE_IMAGE_ARRAY_DYNAMIC_INDEXING |
                    Features::SAMPLED_TEXTURE_DESCRIPTOR_INDEXING |
                    Features::STORAGE_TEXTURE_DESCRIPTOR_INDEXING |
                    Features::UNSIZED_DESCRIPTOR_ARRAY |
                    Features::DRAW_INDIRECT_COUNT,
                hints:
                    Hints::BASE_VERTEX_INSTANCE_DRAWING,
                limits: Limits {
                    //TODO: verify all of these not linked to constants
                    max_bound_descriptor_sets: MAX_DESCRIPTOR_SETS as u16,
                    max_descriptor_set_uniform_buffers_dynamic: 8,
                    max_descriptor_set_storage_buffers_dynamic: 4,
                    max_descriptor_set_sampled_images: full_heap_count,
                    max_descriptor_set_storage_buffers: uav_limit,
                    max_descriptor_set_storage_images: uav_limit,
                    max_descriptor_set_uniform_buffers: full_heap_count,
                    max_descriptor_set_samplers: d3d12::D3D12_MAX_SHADER_VISIBLE_SAMPLER_HEAP_SIZE as _,
                    max_per_stage_descriptor_sampled_images: match features.ResourceBindingTier {
                        d3d12::D3D12_RESOURCE_BINDING_TIER_1 => 128,
                        d3d12::D3D12_RESOURCE_BINDING_TIER_2
                        | d3d12::D3D12_RESOURCE_BINDING_TIER_3
                        | _ => full_heap_count,
                    } as _,
                    max_per_stage_descriptor_samplers: match features.ResourceBindingTier {
                        d3d12::D3D12_RESOURCE_BINDING_TIER_1 => 16,
                        d3d12::D3D12_RESOURCE_BINDING_TIER_2
                        | d3d12::D3D12_RESOURCE_BINDING_TIER_3
                        | _ => d3d12::D3D12_MAX_SHADER_VISIBLE_SAMPLER_HEAP_SIZE
                    } as _,
                    max_per_stage_descriptor_storage_buffers: uav_limit,
                    max_per_stage_descriptor_storage_images: uav_limit,
                    max_per_stage_descriptor_uniform_buffers: match features.ResourceBindingTier {
                        d3d12::D3D12_RESOURCE_BINDING_TIER_1
                        | d3d12::D3D12_RESOURCE_BINDING_TIER_2 => d3d12::D3D12_COMMONSHADER_CONSTANT_BUFFER_API_SLOT_COUNT,
                        d3d12::D3D12_RESOURCE_BINDING_TIER_3
                        | _ => full_heap_count as _,
                    } as _,
                    max_uniform_buffer_range: (d3d12::D3D12_REQ_CONSTANT_BUFFER_ELEMENT_COUNT * 16) as _,
                    max_storage_buffer_range: !0,
                    // Is actually 256, but need space for the descriptors in there, so leave at 128 to discourage explosions
                    max_push_constants_size: 128,
                    max_image_1d_size: d3d12::D3D12_REQ_TEXTURE1D_U_DIMENSION as _,
                    max_image_2d_size: d3d12::D3D12_REQ_TEXTURE2D_U_OR_V_DIMENSION as _,
                    max_image_3d_size: d3d12::D3D12_REQ_TEXTURE3D_U_V_OR_W_DIMENSION as _,
                    max_image_cube_size: d3d12::D3D12_REQ_TEXTURECUBE_DIMENSION as _,
                    max_image_array_layers: d3d12::D3D12_REQ_TEXTURE2D_ARRAY_AXIS_DIMENSION as _,
                    max_texel_elements: 0,
                    max_patch_size: 0,
                    max_viewports: d3d12::D3D12_VIEWPORT_AND_SCISSORRECT_OBJECT_COUNT_PER_PIPELINE as _,
                    max_viewport_dimensions: [d3d12::D3D12_VIEWPORT_BOUNDS_MAX as _; 2],
                    max_framebuffer_extent: hal::image::Extent { //TODO
                        width: 4096,
                        height: 4096,
                        depth: 1,
                    },
                    max_compute_work_group_count: [
                        d3d12::D3D12_CS_DISPATCH_MAX_THREAD_GROUPS_PER_DIMENSION,
                        d3d12::D3D12_CS_DISPATCH_MAX_THREAD_GROUPS_PER_DIMENSION,
                        d3d12::D3D12_CS_DISPATCH_MAX_THREAD_GROUPS_PER_DIMENSION,
                    ],
                    max_compute_work_group_invocations: d3d12::D3D12_CS_THREAD_GROUP_MAX_THREADS_PER_GROUP as _,
                    max_compute_work_group_size: [
                        d3d12::D3D12_CS_THREAD_GROUP_MAX_X,
                        d3d12::D3D12_CS_THREAD_GROUP_MAX_Y,
                        d3d12::D3D12_CS_THREAD_GROUP_MAX_Z,
                    ],
                    max_vertex_input_attributes: d3d12::D3D12_IA_VERTEX_INPUT_RESOURCE_SLOT_COUNT as _,
                    max_vertex_input_bindings: 31, //TODO
                    max_vertex_input_attribute_offset: 255, // TODO
                    max_vertex_input_binding_stride: d3d12::D3D12_REQ_MULTI_ELEMENT_STRUCTURE_SIZE_IN_BYTES as _,
                    max_vertex_output_components: 16, // TODO
                    min_texel_buffer_offset_alignment: 1, // TODO
                    min_uniform_buffer_offset_alignment: d3d12::D3D12_CONSTANT_BUFFER_DATA_PLACEMENT_ALIGNMENT as _,
                    min_storage_buffer_offset_alignment: 4, // TODO
                    framebuffer_color_sample_counts: sample_count_mask,
                    framebuffer_depth_sample_counts: sample_count_mask,
                    framebuffer_stencil_sample_counts: sample_count_mask,
                    max_color_attachments: d3d12::D3D12_SIMULTANEOUS_RENDER_TARGET_COUNT as _,
                    buffer_image_granularity: 1,
                    non_coherent_atom_size: 1, //TODO: confirm
                    max_sampler_anisotropy: 16.,
                    optimal_buffer_copy_offset_alignment: d3d12::D3D12_TEXTURE_DATA_PLACEMENT_ALIGNMENT as _,
                    optimal_buffer_copy_pitch_alignment: d3d12::D3D12_TEXTURE_DATA_PITCH_ALIGNMENT as _,
                    min_vertex_input_binding_stride_alignment: 1,
                    .. Limits::default() //TODO
                },
                format_properties: Arc::new(FormatProperties::new(device)),
                private_caps: Capabilities {
                    heterogeneous_resource_heaps,
                    memory_architecture,
                },
                workarounds,
                heap_properties,
                memory_properties: adapter::MemoryProperties {
                    memory_types,
                    memory_heaps,
                },
                is_open: Arc::new(Mutex::new(false)),
            };

            let queue_families = QUEUE_FAMILIES.to_vec();

            adapters.push(adapter::Adapter {
                info,
                physical_device,
                queue_families,
            });
        }
        adapters
    }

    unsafe fn create_surface(
        &self,
        has_handle: &impl raw_window_handle::HasRawWindowHandle,
    ) -> Result<window::Surface, hal::window::InitError> {
        match has_handle.raw_window_handle() {
            raw_window_handle::RawWindowHandle::Windows(handle) => {
                Ok(self.create_surface_from_hwnd(handle.hwnd))
            }
            _ => Err(hal::window::InitError::UnsupportedWindowHandle),
        }
    }

    unsafe fn destroy_surface(&self, _surface: window::Surface) {
        // TODO: Implement Surface cleanup
    }
}

#[derive(Copy, Clone, Debug, Eq, Hash, PartialEq)]
pub enum Backend {}
impl hal::Backend for Backend {
    type Instance = Instance;
    type PhysicalDevice = PhysicalDevice;
    type Device = Device;
    type Surface = window::Surface;

    type QueueFamily = QueueFamily;
    type CommandQueue = CommandQueue;
    type CommandBuffer = command::CommandBuffer;

    type Memory = resource::Memory;
    type CommandPool = pool::CommandPool;

    type ShaderModule = resource::ShaderModule;
    type RenderPass = resource::RenderPass;
    type Framebuffer = resource::Framebuffer;

    type Buffer = resource::Buffer;
    type BufferView = resource::BufferView;
    type Image = resource::Image;
    type ImageView = resource::ImageView;
    type Sampler = resource::Sampler;

    type ComputePipeline = resource::ComputePipeline;
    type GraphicsPipeline = resource::GraphicsPipeline;
    type PipelineLayout = resource::PipelineLayout;
    type PipelineCache = ();
    type DescriptorSetLayout = resource::DescriptorSetLayout;
    type DescriptorPool = resource::DescriptorPool;
    type DescriptorSet = resource::DescriptorSet;

    type Fence = resource::Fence;
    type Semaphore = resource::Semaphore;
    type Event = ();
    type QueryPool = resource::QueryPool;
}

fn validate_line_width(width: f32) {
    // Note from the Vulkan spec:
    // > If the wide lines feature is not enabled, lineWidth must be 1.0
    // Simply assert and no-op because DX12 never exposes `Features::LINE_WIDTH`
    assert_eq!(width, 1.0);
}

#[derive(Clone, Copy, Debug, Default)]
struct FormatInfo {
    properties: f::Properties,
    sample_count_mask: u8,
}

#[derive(Debug)]
pub struct FormatProperties {
    info: Box<[Mutex<Option<FormatInfo>>]>,
    device: native::Device,
}

impl Drop for FormatProperties {
    fn drop(&mut self) {
        unsafe {
            self.device.destroy();
        }
    }
}

impl FormatProperties {
    fn new(device: native::Device) -> Self {
        let mut buf = Vec::with_capacity(f::NUM_FORMATS);
        buf.push(Mutex::new(Some(FormatInfo::default())));
        for _ in 1..f::NUM_FORMATS {
            buf.push(Mutex::new(None))
        }
        FormatProperties {
            info: buf.into_boxed_slice(),
            device,
        }
    }

    fn resolve(&self, idx: usize) -> FormatInfo {
        let mut guard = self.info[idx].lock();
        if let Some(info) = *guard {
            return info;
        }
        let format: f::Format = unsafe { mem::transmute(idx as u32) };
        let is_compressed = format.surface_desc().is_compressed();
        let dxgi_format = match conv::map_format(format) {
            Some(format) => format,
            None => {
                let info = FormatInfo::default();
                *guard = Some(info);
                return info;
            }
        };

        let properties = {
            let mut props = f::Properties::default();
            let mut data = d3d12::D3D12_FEATURE_DATA_FORMAT_SUPPORT {
                Format: dxgi_format,
                Support1: unsafe { mem::zeroed() },
                Support2: unsafe { mem::zeroed() },
            };
            assert_eq!(winerror::S_OK, unsafe {
                self.device.CheckFeatureSupport(
                    d3d12::D3D12_FEATURE_FORMAT_SUPPORT,
                    &mut data as *mut _ as *mut _,
                    mem::size_of::<d3d12::D3D12_FEATURE_DATA_FORMAT_SUPPORT>() as _,
                )
            });
            let can_buffer = 0 != data.Support1 & d3d12::D3D12_FORMAT_SUPPORT1_BUFFER;
            let can_image = 0
                != data.Support1
                    & (d3d12::D3D12_FORMAT_SUPPORT1_TEXTURE1D
                        | d3d12::D3D12_FORMAT_SUPPORT1_TEXTURE2D
                        | d3d12::D3D12_FORMAT_SUPPORT1_TEXTURE3D
                        | d3d12::D3D12_FORMAT_SUPPORT1_TEXTURECUBE);
            let can_linear = can_image && !is_compressed;
            if can_image {
                props.optimal_tiling |= f::ImageFeature::SAMPLED | f::ImageFeature::BLIT_SRC;
            }
            if can_linear {
                props.linear_tiling |= f::ImageFeature::SAMPLED | f::ImageFeature::BLIT_SRC;
            }
            if data.Support1 & d3d12::D3D12_FORMAT_SUPPORT1_IA_VERTEX_BUFFER != 0 {
                props.buffer_features |= f::BufferFeature::VERTEX;
            }
            if data.Support1 & d3d12::D3D12_FORMAT_SUPPORT1_SHADER_SAMPLE != 0 {
                props.optimal_tiling |= f::ImageFeature::SAMPLED_LINEAR;
            }
            if data.Support1 & d3d12::D3D12_FORMAT_SUPPORT1_RENDER_TARGET != 0 {
                props.optimal_tiling |=
                    f::ImageFeature::COLOR_ATTACHMENT | f::ImageFeature::BLIT_DST;
                if can_linear {
                    props.linear_tiling |=
                        f::ImageFeature::COLOR_ATTACHMENT | f::ImageFeature::BLIT_DST;
                }
            }
            if data.Support1 & d3d12::D3D12_FORMAT_SUPPORT1_BLENDABLE != 0 {
                props.optimal_tiling |= f::ImageFeature::COLOR_ATTACHMENT_BLEND;
            }
            if data.Support1 & d3d12::D3D12_FORMAT_SUPPORT1_DEPTH_STENCIL != 0 {
                props.optimal_tiling |= f::ImageFeature::DEPTH_STENCIL_ATTACHMENT;
            }
            if data.Support1 & d3d12::D3D12_FORMAT_SUPPORT1_SHADER_LOAD != 0 {
                //TODO: check d3d12::D3D12_FORMAT_SUPPORT2_UAV_TYPED_LOAD ?
                if can_buffer {
                    props.buffer_features |= f::BufferFeature::UNIFORM_TEXEL;
                }
            }
            if data.Support2 & d3d12::D3D12_FORMAT_SUPPORT2_UAV_ATOMIC_ADD != 0 {
                //TODO: other atomic flags?
                if can_buffer {
                    props.buffer_features |= f::BufferFeature::STORAGE_TEXEL_ATOMIC;
                }
                if can_image {
                    props.optimal_tiling |= f::ImageFeature::STORAGE_ATOMIC;
                }
            }
            if data.Support2 & d3d12::D3D12_FORMAT_SUPPORT2_UAV_TYPED_STORE != 0 {
                if can_buffer {
                    props.buffer_features |= f::BufferFeature::STORAGE_TEXEL;
                }
                if can_image {
                    props.optimal_tiling |= f::ImageFeature::STORAGE;
                }
            }
            //TODO: blits, linear tiling
            props
        };

        let sample_count_mask = if is_compressed {
            // just an optimization to avoid the queries
            1
        } else {
            let mut mask = 0;
            for i in 0..6 {
                let mut data = d3d12::D3D12_FEATURE_DATA_MULTISAMPLE_QUALITY_LEVELS {
                    Format: dxgi_format,
                    SampleCount: 1 << i,
                    Flags: 0,
                    NumQualityLevels: 0,
                };
                assert_eq!(winerror::S_OK, unsafe {
                    self.device.CheckFeatureSupport(
                        d3d12::D3D12_FEATURE_MULTISAMPLE_QUALITY_LEVELS,
                        &mut data as *mut _ as *mut _,
                        mem::size_of::<d3d12::D3D12_FEATURE_DATA_MULTISAMPLE_QUALITY_LEVELS>() as _,
                    )
                });
                if data.NumQualityLevels != 0 {
                    mask |= 1 << i;
                }
            }
            mask
        };

        let info = FormatInfo {
            properties,
            sample_count_mask,
        };
        *guard = Some(info);
        info
    }
}